Ken Griffin owns NYC’s priciest condo. Mamdani wants to hike his property tax — and others.

• NYC's mayoral frontrunner has a plan to overhaul the city's property tax system.
• It involves an analysis of billionaire Ken Griffin's 220 Central Park South apartment.
• Here's what it could mean for NYC homeowners from Staten Island to the Bronx.

When Ken Griffin purchased the most expensive home in America in 2019, it came with a hidden discount.

The palatial four-floor apartment at 220 Central Park South, which cost the billionaire founder of the hedge fund Citadel nearly $240 million, is taxed at about half the rate of the average condo in the city, data shows.

Now, Zohran Mamdani, the 33-year-old self-described socialist who won the Democratic primary for New York City mayor, wants Griffin — and scores of other wealthy homeowners in the city — to pay more. His plan, if instituted, could upend tax bills from Staten Island to Billionaire's Row in Manhattan.

In a policy memo published by his campaign, Mamdani pointed to Griffin's Central Park South apartment as an example of why he thinks an overhaul of the city's byzantine system is necessary.

Without mentioning Griffin by name, the memo called out the taxes charged for an apartment at 220 Central Park South that cost $228 million, what the memo described as "the most expensive home ever sold in the United States." (News reports at the time of the sale said Griffin bought the apartment for $238 million.)

The memo proposed taxing the apartment, and others like it across the city, closer to their actual sales values versus the complex formulas currently used by the city's Department of Finance, which valued Griffin's apartment at just $15 million on his most recent tax bill. Mamdani's memo said this change would lead to an annual property tax bill on Griffin's Central Park pad of $3 million — more than three times what it currently pays. Other New Yorkers could also see their costs rise — or fall — depending on where they live and the sales value of their homes.

A spokesperson for Griffin declined to comment. Records from the city's Department of Finance show Griffin's Central Park property was charged $841,000 in property taxes for 2025/26..

The $841,000 bill means that Griffin pays 35 cents of taxes per hundred dollars of the apartment's sales value. That's less than half the tax burden paid by condo owners across the city on average, according to a 2021 report by a tax reform commission tapped by the previous NYC mayor, Bill de Blasio. The average condo in the city pays 74 cents of taxes per $100 of sales value, according to the report.

Raising taxes on Brooklyn brownstones

Mamdani said the city's current method, which calculates values for condos and coops by comparing them with rentals, "heavily favors luxury and super-luxury apartments."

He said he would embrace reforms recommended by the 2021 tax commission, which suggested NYC use a "sales-based methodology to value all properties." That methodology, he said, would lower tax payments for homeowners in neighborhoods like Jamaica in Queens and Brownsville in Brooklyn "while raising the amount paid in the most expensive Brooklyn brownstones."

Tax experts agreed that the current tax system tends to favor tony neighborhoods like the Upper East Side, Greenwich Village, and Park Slope. Poorer and working-class communities in the Bronx and Staten Island have historically paid more as a percentage of the sales value of their real estate, they said.

Sebastian Hallum Clarke, a product manager at Google Maps who has studied the city's property tax system in his free time, highlighted that dichotomy in a blog post. Clarke detailed how a 96-unit rental apartment building in the Queens neighborhood of Jackson Heights paid nearly six times as much in annual property taxes as a single-family Upper East Side mansion, even though the city's Department of Finance estimates similar values — $6.6 million versus $5.5 million — for the two.

"Every dollar in cost for a rental gets passed on ultimately to the renters themselves," Clarke said. It's "a broken system that is just completely unfair in terms of how much tax different classes of property are paying."

Part of the disparity is attributable to state-mandated caps that prevent the city from raising the assessed value on one- to three-family homes by more than 6% per year and 20% over five years.

It remains to be seen whether Mamdani, if he wins the mayoralty, prioritizes property tax reform in an agenda packed with bold promises, including free bus service, a rent freeze, and affordable housing development. Other mayors have pledged to fix the system only to punt on the complex and politically fraught issue.

"The Dinkins administration did a property tax reform commission," said Martha Stark, a former commissioner of the Department of Finance during Michael Bloomberg's mayoralty, noting how long the system has been under scrutiny.

"I just can't imagine that Mamdani would elevate that to the top of his priority list in the first term," said James Parrott, an economist who was on the 2021 tax advisory commission.